Possible mechanism of oxygen radical production by human eosinophils mediated by K+ channel activation

Quinidine hydrochloride, as potent K+ channel blocker, reduced luminol-dependent chemiluminescence products evoked by the addition of the calcium ionophore A23187 to eosinophils from patients with hypereosinophilic syndrome (n = 3) in a concentration-dependent manner (10-5 mM quinidine). A23187 is known to cause increases in intracellular Ca2+ concentrations in eosinophils. Our results indicate that the production of reactive oxygen species by human eosinophils may be affected by Ca(+)-activated K+ channels.